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Real-time crystallization in fluorinated parylene probed by conductivity spectra

Khazaka, Rabih and Locatelli, Marie-Laure and Diaham, Sombel and Tenailleau, Christophe and Kumar, Rakesh Real-time crystallization in fluorinated parylene probed by conductivity spectra. (2014) Applied Physics Letters, 104 (11). 112902. ISSN 0003-6951

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Official URL: http://dx.doi.org/10.1063/1.4868646

Abstract

Dielectric relaxation spectroscopy experiments were performed at high temperature on fluorinated parylene films during the occurrence of the isothermal crystalline phase transition. For this polymer, since the difference between the glass transition temperature (Tg ) and the phase transition temperature (Tc ) is very strong (Tc  ≥ 4Tg ), segmental and dipolar relaxation usually used to probe the crystallization are not shown in the experiment frequency window (10−1 to 106 Hz) during the crystallization. The charge diffusion becomes the only electrical marker that allows probing the phase transition. During the transition phase, a continuous decrease of about two orders of magnitude is observed in the conductivity values below an offset frequency (fc ) with a tendency to stabilization after 600 min. Below the offset frequency, the decrease of the normalized conductivity to the initial value as function of time is frequency independent. The same behavior is also observed for the fc values that decrease from 160 Hz to about 20 Hz. Above the offset frequency, the electronic hopping mechanism is also affected by the phase transition and the power law exponent (n) of the AC conductivity shows a variation from 0.7 to 0.95 during the first 600 min that tend to stabilize thereafter. Accordingly, three parameters (n, fc , and AC conductivity values for frequencies below f c) extracted from the AC conductivity spectra in different frequency windows seem suitable to probe the crystalline phase transition.

Item Type:Article
Additional Information:Thanks to AIP Publishing. The definitive version is available at http://scitation.aip.org The original PDF of the article can be found at Applied Physics Letters website : http://scitation.aip.org/content/aip/journal/apl/104/11/10.1063/1.4868646
HAL Id:hal-01165180
Audience (journal):International peer-reviewed journal
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Institution:French research institutions > Centre National de la Recherche Scientifique - CNRS (FRANCE)
Université de Toulouse > Institut National Polytechnique de Toulouse - INPT (FRANCE)
Université de Toulouse > Université Toulouse III - Paul Sabatier - UPS (FRANCE)
Other partners > Specialty Coating Systems - SCS (USA)
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Deposited By: cirimat webmestre
Deposited On:18 Jun 2015 13:27

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